1. Field of the Invention
The present invention relates to electrical connectors, especially terminal blocks, with active electrical components between signal paths and ground.
2. Description of the Prior Art
Active, or non-resistive, capacitive elements can be incorporated into connectors to reduce cross-talk, improve impedance matching, filter out EMI/RFI (electromagnetic or radio-frequency interference), suppress transients (voltage “spikes”), and for various other purposes. Such elements are sometimes known as “chip capacitors” or simply “chips” and will be so referred here. The chips may be placed across two signal lines, from signal lines to ground, or otherwise as appropriate.
The chips may be held in a hole in the insulating housing of the connector, which provides both location and protection for the chip. This is illustrated by U.S. Pat. No. 6,036,545 to Caviness et al, entitled “Decoupled BNC Connector.” It discloses a board mountable BNC electrical connector 10 with a spark gap feature that protects the connector against exposure to elevated voltages. The Caviness BNC connector is adapted to be mounted onto a printed circuit (PC) board to make grounding contact. The connector includes a grounding clip 76 which is mounted under the connector body or housing so as to be in contact with the PC board. As seen in FIG. 5, capacitors (chips) 68 are held in slots 66 to contact the conductive shell portion 18 on the inside and, on the outside, the upward-extending tines or arms 82 of the grounding clip 76. The grounding clip 76 is mounted to the PC board with board locks 84 that project downwardly from the base portion 80 of the clip 76. The board locks clip into holes in the board.
In the Caviness design only two chips can make contact with the shell portion 18.
A spark gap tab 74 projects up from the base 80 (in the opposite direction from the board locks 84). As best seen in FIG. 5, the tab 74 is fitted into a key way 72. This is the only apparent mechanical connection between the grounding clip 76 and the plastic housing, and it is not a strong connection. The narrow width of the tab 74, combined with the small overlap on the shoulder of the key way and the relatively weak nature of the insulating material, make for failure under any but the mildest stresses under pulling-out forces, and sliding of the tab in the key way could also be a problem.
In addition, the assembly of the tab 74 into the key way 72, followed by the bending of the conductor leads 54, is difficult to automate or perform rapidly.
Plass, in FIG. 1 of U.S. Pat. No. 5,242,318, shows an elongated plate 9 which Plass calls a filter carrier. It has a central opening, around which are contact tongues 9.1 that hold a thin planar filter 10. FIG. 1 of Plass, an exploded view with parts separated longitudinally, shows the filter 10 slid out transversely to the longitudinal direction, indicating that the tongues 9.1 provide a slot for the filter 10.
U.S. Pat. No. 4,500,159 to Briones et al. discloses a filter connector (24; 90; 116) with an electrically conductive shell (60; 91; 118) and a dielectric body (50; 93; 120) mounted to the shell and having a sidewall 52, a row of passages (56; 95; 123) extending through with each receiving an electrical contact (51; 97; 124), and a row of separated cavities (58; 99; 122) extending inwardly from the sidewall in a direction transverse to that of the passages with each communicating with only one respective passage. A monolithic chip-type capacitor chip 80, including active and ground electrodes, is disposed in each cavity. Their inner ends touch individual signal conductors, and their outer ends are pressed by resilient conductive spring tines 75 (see FIG. 3). The tines are bent over from fingers extending from the flat plate of a spring member 70. There are two members 70, one above and one below.
A resilient conductor (90) pressing against a chip (80) is disclosed in U.S. Pat. No. 5,340,334 to Nguyen, in FIG. 5.
U.S. Pat. No. 5,895,293, issued to Brandenberg et al, discloses a filtered terminal block assembly with a dielectric insert (20) having a cavity (48) including various-sized sub-cavities including a pocket (50) and a bore (52). The insert (20) is mounted in an opening (46) on a ground plate (16), and a ground member (22) extends from the plate to enclose the dielectric insert. The dielectric insert has a bore (52) and a cavity (48), in which a filter element (24, 26) is disposed. The filter element 24 is annular/cylindrical in shape, like a section of tubing; see FIG. 3. An electrical contact (14) extends through the filter element (24, 26). An outer end of the filter element (24, 26) is electrically connected to the electrical contact (14), and a ground member (22) is electrically connected between the filter element (24, 26) and the ground plate (16). An electrically-conductive thixotropic material (54) in a pocket (50) and along an inner surface of the cavity(48) electrically connects an inner end of the filter element (24, 26) to the electrical contact (14).
The Brandenberg connector cannot be adapted to multiple chips.
In U.S. Pat. No. 4,950,185, issued to Boutros et al, a planar filter array isolated from mechanical and thermal stresses by an arrangement of resilient planar gaskets which sandwich the array and by electrical contact springs which further isolate the array from mechanical and thermal stresses while permitting electrical connection to the individual filters.
U.S. Pat. No. 5,397,250 discloses a modular jack connector arranged to optionally accommodate both a ferrite block inductor arrangement and chip capacitors. The connector can be assembled and all components secured in place in four insertion steps, without soldering or other bonding techniques.
The prior art does not disclose a structure allowing more than one or two chips to be coupled between a conductor, such as a signal lead, and a ground plane. Neither does it disclose a secure arrangement of a ground plane for a terminal block, or any means for retaining a grounding sheet.